Why should a text messenger be fun? It's a communication tool, not a game...
The stickers accessed via the sticker button left of the textbox. You can add stickers by going to https://signalstickers.org and click on add stickers. And you can add them some way if you receive a new one from a contact.
What is a list of links? Links you have sent/recieved previously?
Afaik Bayern German is closer to Austrian German, than Hochdeutch. Hungarian doesn't have that kind of variants because the language is the same everywhere, but 1 million Hungarians live in neighbouring countries.
Do you expect every South American user to set that up correctly? What about languages without country, I guess you show the spanish version to basques living in France?
And I could continue if you want.